1. Field of the Invention
The present invention relates generally to methods and apparatus for imprinting images on the surfaces of three-dimensional objects. More particularly, the invention concerns a novel, improved method and apparatus for non-contact, high-quality, distortion-free printing of images on non-planar surfaces of three-dimensional objects using ink jet printing technology.
2. Discussion of the Prior Art
Various types of image transfer techniques have been suggested in the past for imprinting images on a number of different material surfaces including cloth, wood, metal and ceramics. A very common technique, which has been widely used, is silk screening. However, such a technique is generally limited to printing on smooth, flat surfaces. Further, such technique produces a relatively low quality prints when compared to that produced by lithography, gravure, letterpress sublimation and laser printing.
When the image is to be transferred to a metal surface, prior art sublimation techniques are frequently used. For example, Blake et al, U.S. Pat. No. 3,484,342 issued Dec. 16, 1969 and Fromson et al, U.S. Pat. No. 4,201,821 issued May 6, 1980 both suggest decorating unsealed and coated anodized aluminum using sublimation techniques. However, Sublimation processes also have substantial drawbacks, particularly when the surface of the object, which is printed, is non-planar. Transferring an image or graphic to a sphere or curved, cylindrically tapered surface by means of sublimation, is extremely difficult and such an approach, if achievable at all, would typically result in a poor quality, highly distorted image.
When printing on non-planar surfaces is required, several techniques have been suggested. For example, U.S. Pat. No. 4,741,288 issued to Stirbis et al discloses an apparatus for decorating a cylindrical can. The Stirbis et al apparatus makes use of a multiple station ink supply and a transfer apparatus for transferring ink from an ink fountain to a rotatable inking blanket wheel through a plate cylinder. The apparatus includes an ink image registration adjustment apparatus and an axial and circumferential tightness control apparatus operatively associated with each plate cylinder and each ink supply and transfer apparatus. In addition to techniques involving the use of rotatable inking wheels such as described in Stirbis et al, other techniques, which have been suggested for imprinting images on non-planar surfaces, include electrophotographic imaging and magnetic imaging. As a general rule, these techniques have met with limited commercial success.
U.S. Pat. No. 5,831,641 issued to Carlson discloses a method and apparatus for imprinting images on non-planar surfaces, including the surfaces of various types of three-dimensional articles, such as baseball bats. The apparatus includes a modified ink jet plotter coupled with an article positioning apparatus which functions to automatically maintain the surface of the article to be printed within a plane substantially parallel to and slightly spaced apart from the place within which the ink jet nozzles of the ink jet plotter reside.
Another prior art technique, which is frequently used to decorate surfaces, such as anodized aluminum surfaces, involves the use of transfer films. These films typically overlay the metal surface and undesirably, are subject to film deterioration and unattractive abrasion. A very popular prior art printing technique, which has found wide acceptance in recent years, is ink jet printing. Within perhaps the last five years this technology has become the dominant technology for printing color images and graphics in the office and home markets. Ink jet printing basically involves a process whereby ink particles are projected in a continuous stream toward the surface to be imprinted using appropriate computer control to create text and graphics on the printing substrate. A number of different types of ink jet printers/plotters are readily commercially available from sources such as Calcomp, Packard Bell, NEC Technologies and Mutoh America, Inc.
As will be better understood from the discussion which follows, the method and apparatus of the present invention overcomes most of the problems encountered in prior art attempts to print detailed images on non-planar surfaces by employing a uniquely modified prior art ink jet image transfer technique.